The technique of pancreatic islet transplantation into type-1 diabetic patients, who are unable to survive without the administration of insulin, that is, who are in an insulin dependent diabetes mellitus, is garnering a great deal of public awareness and efforts are being made, mainly in Europe and the United States, to establish this technique as a clinical treatment.
Pancreatic islet transplantation refers to cellular tissue transplantation in which pancreatic islet cell groups, which play a central role in blood sugar regulation in the body, are administered by infusion into the portal vein. Islet transplantation is minimally invasive for the transplant recipient and is regarded as the treatment nearest to ideal for type-1 diabetic patients.
In 2000, at the University of Alberta in Edmonton, Canada, a successful trial of clinical islet transplantation was reported. Since this report, approximately 300 islet transplantations have been performed in the 4 years, mainly in Europe and the United States. These islet transplantations have been carried out on the basis of the Edmonton protocol established at the University of Alberta.
However, with the technology heretofore, consistent islet yields have not been obtained, even in islet transplantation from brain-dead donors carried out in Europe and the United States, and in some instances the transplanted islets have also not functioned effectively. Moreover, even when considered on a worldwide basis, there have been almost no successful cases of islet transplantation from non-heart-beating donors, where the conditions are worse than with brain-dead donors, and in fact islet transplantation from non-heart-beating donors has to date not been possible.
To raise the success rates of islet transplantation and also to achieve successful islet transplantation from non-heart-beating donors, it is important to transplant a large population of islets fit for transplantation. Therefore, there has been strong demand for improvements in islet isolation technology in order to raise the yield of transplantable islets.
On the other hand, in the medical treatment of transplantation, a method has been reported in which ulinastatin or a ulinastatin substitute is administered post-transplant to organ transplant patients (See Japanese Unexamined Patent Publication No. 2002-20309).
Further, a solution for perfusion or storage of organs that are destined for transplantation has been reported, wherewith excellent results were obtained in lung transplantation (refer to Japanese Unexamined Patent Publication No. H6-40801).
However, an optimal means for islet transplantation, particularly with regard to islet isolation and purification technology, remains elusive.